JP2605362B2 - Rotary encoder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary encoder, and more particularly to a rotary encoder that facilitates attachment to a shaft to be measured.

2. Description of the Related Art Conventionally, in a high-resolution rotary encoder, as shown in FIG. 4, a hollow shaft 42 to which a code plate 41 is fixed is fitted to a shaft 43 to be measured with a gap therebetween, and is axially oriented. Are positioned by engaging one end of the hollow shaft 42 with a contact surface 43a formed on the shaft 43 to be measured, and bolted to a plurality of circumferential positions of a fixing ring 44 screwed to the end of the shaft 43 to be measured. The other end of the hollow shaft 42 is fixed by pressing the other end of the hollow shaft 42 via a pressing plate 46 at 45, and the tip of a screw 47 screwed by being radially penetrated at a plurality of circumferential positions of the hollow shaft 42 in the radial direction. The screw 47 is configured to be brought into contact with the outer peripheral surface of the shaft 43 to be measured and adjusted so that the axis of the code plate 41 and the axis of the shaft 43 to be measured coincide. A detector 48 for detecting the rotational position of the code plate 41 is provided.
Is mounted on the fixed side via a bracket 49 so that the position can be adjusted.

On the other hand, in a rotary encoder having relatively low resolution, as shown in FIG. 5, a hollow rotary shaft 52 to which a code plate 51 is fixed is rotatably supported by a support member 54 via a bearing 53, and a support member 54 is provided. A detector 55 that detects the rotational position of the code plate 51 is attached to the unit 54, and when installed, the hollow rotating shaft 52 is fitted to the measured shaft 56 and screwed to the end of the measured shaft 56. The fixing nut 57 is fastened and fixed to the contact surface 56a. Further, in order to prevent the rotation of the support member 54, the outer peripheral portion of the annular leaf spring 58 perpendicular to the rotation axis is fixed to the fixed side with bolts 59a, and the inner peripheral portion thereof is bolted to the support member 54. Fastened and fixed at 59b.

Problems to be Solved by the Invention By the way, in the mounting configuration as shown in FIG. 4, the code plate 41 is directly mounted on the shaft 43 to be measured.
Can be mounted with little eccentricity to the shaft 43 to be measured, the accumulated pitch error is small, and it is possible to correspond to a high-resolution rotary encoder. This must be performed simultaneously on site, and during installation work in which the working environment is not good, it is necessary to perform assembly adjustment of the rotary encoder such as output waveform adjustment, which causes a problem that it takes a lot of time and effort.

On the other hand, in the mounting configuration shown in FIG. 5, the mounting operation is simple because the rotary encoder is unitized, but the code plate 51 and the code plate 51 are covered by the fitting gap between the shaft to be measured 56 and the hollow rotary shaft 52. There is a problem that eccentricity between the measurement shafts 56 is inevitable, the accumulated pitch error becomes large, and it is not possible to cope with a high-resolution rotary encoder.

Further, since the support member 54 is fixed to the inner peripheral portion of the annular leaf spring 58 having the outer peripheral portion fixed to the fixed side, the restraining force due to the rigidity of the leaf spring 58 is large, and the support member 54 and the measurement target are measured. There is also a problem that a large load variation occurs in the bearing 53 during rotation due to the eccentricity of the shaft 56, which causes rotation unevenness.

In FIG. 5, when the inner diameter of the hollow rotary shaft 52 is increased, a large-diameter bearing 53 is required.
Since the rotation accuracy of the shaft 51 is reduced and the gap between the code plate 51 and the detector 55 may fluctuate and a detection error may occur, the center of the shaft between the shaft 56 to be measured and the hollow shaft 52 may be adjusted. It was not conceivable to interpose the means.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide a rotary encoder that can be easily mounted, has a small accumulated pitch error, and can support high-resolution position detection.

Means for Solving the Problems In order to achieve the above object, the present invention provides a code plate, a hollow rotary shaft to which the code plate is fixed, a rotatable support of the hollow rotary shaft via a bearing, and a rotation of the code plate. A support member on which a detector for detecting a position is mounted, and fixing means interposed between the inner peripheral surface of the hollow rotary shaft and the measured shaft to fix the hollow rotary shaft to the measured shaft so that the center of the hollow rotary shaft can be adjusted. And a measurement surface formed on the outer peripheral surface of the hollow rotary shaft.

Preferably, a laser method in which a laser beam is irradiated from a laser light source to a code plate, and light-dark stripes of a Fraunhofer diffraction image generated by a slit regularly formed on the code plate are irradiated on a photodetector through the slit. Is used. Preferably, the measuring surface is formed at both end protruding portions of the hollow rotary shaft, and the fixing means comprises a pair of wedge-shaped sleeves and a clamped means provided with a chevron sleeve which are attracted to each other by a screw mechanism.

Further, a connecting means is used in which the supporting member is fixed only in the direction of rotation about the axis of the hollow rotary shaft, and is connected to the fixed side so that it can float in other directions. The coupling means includes an engagement pin protruding from the support member in the radial direction, and a fixed-side engagement member that is engaged with the engagement pin in the circumferential direction. It is preferable to provide a flexible wire rod which is arranged in a tangential direction with respect to the circumference around the center and whose intermediate part is fixed to the support member, and a fixing bracket which fixes both ends to the fixed side.

According to the rotary encoder of the present invention, the code plate, the detector, the hollow rotary shaft, the bearing, and the support member are combined into a unit, so that it can be easily mounted simply by mounting it on the shaft to be measured. In addition, since the fixing means for fixing the hollow rotary shaft to the shaft to be measured so that the shaft center can be adjusted is provided, the eccentricity is reduced by adjusting the shaft center while measuring the shaft center position on the measurement surface, and the cumulative pitch error is reduced. Can be reduced, and high-resolution ones can be handled.

In addition, if the detector is a laser type and a narrow beam-like light and dark fringe is detected by Fraunhofer diffraction, even if the gap between the code plate and the detector is set large, there is no possibility that a detection error occurs, By providing the fixing means, the diameters of the hollow rotary shaft and the bearing are increased, the bearing accuracy is reduced, and no detection error occurs even if the surface deflection of the code plate increases.

Further, when the measurement surfaces are provided at both ends of the hollow rotary shaft, the detection accuracy of the shaft center is increased.

Further, by fixing the support member only in the rotation direction and allowing the support member to float in the other direction, the load does not fluctuate in the bearing due to the rotation, so that the rotation system is not adversely affected.

Embodiment An embodiment of the present invention will be described below with reference to FIG. 1 and FIG.

In FIG. 1, reference numeral 1 denotes a hollow rotary shaft which is fitted to the shaft 2 to be measured, and a support flange 3 of a code plate 4 is provided on an outer periphery thereof. The inner peripheral portion of the code plate 4 is abutted and fixed to one receiving surface of the support flange 3. The hollow rotary shaft 1 is rotatably supported by a support member 7 formed of an annular plate via a pair of ball bearings 6. A detector 8 for detecting the rotational position of the code plate 4 is provided on the support member 7. The detector 8 irradiates the code plate 4 with a laser beam from a laser light source, and irradiates the light detecting element with bright and dark fringes of a Fraunhofer diffraction image generated by a slit regularly formed on the code plate 4 through the slit. It is configured as follows.

9 is a cover for covering the code plate 4 and the detector 8,
The outer peripheral portion is fixed to the outer periphery of the support member 7. Reference numeral 6a denotes a fixing nut of the bearing 6, which is screwed to the outer periphery of the hollow rotary shaft 1. The outer peripheral surfaces of both ends of the hollow rotary shaft 1 on the outer side in the axial direction from the cover 9 and the fixing nut 6a are formed on the measurement surfaces 10a and 10b formed exactly in the same axis as the code plate 4. .

Reference numeral 11 denotes a fixing means interposed between the outer peripheral surface of the shaft 2 to be measured and the inner peripheral surface of the hollow rotary shaft 1 for fixing the hollow rotary shaft to the shaft to be measured so that the center of the hollow rotary shaft can be adjusted. A pair of wedge-shaped sleeves 12a and 12b drawn toward each other, and a chevron sleeve engaged with the inner circumference of these wedge-shaped sleeves 12a and 12b
14 and a clamp means comprising a chevron sleeve 15 engaging with the outer periphery. The outer angled sleeve 15 is divided into two parts at the center position in the axial direction, and the distance piece for adjustment is used.
16 are interposed.

2 (a) and 2 (b) are provided on the outer periphery of the support member 7.
As shown in (1), there is provided a coupling means 17 for fixing the support member 7 only in the rotation direction, and connecting the support member 7 to the fixing portion 18 in a floating state in the other direction. The coupling means 17 includes an engaging pin 19 protruding from the support member 7 in the radial direction, a locking bracket 20 engaging the engaging pin 19 from one side in the circumferential direction, and a pressing member engaging from the other side. Locking bracket consisting of lock pin 21
Reference numeral 20 is attached to the fixing portion 18, and the pressing / locking pin 21 is attached to the locking bracket 20 so as to be able to move back and forth, and is urged by a spring 22 to protrude.

Next, the rotary encoder having the above configuration is
The procedure for attaching to is described. The hollow rotating shaft 1 is connected to the shaft 2 to be measured.
The fixing means 11 with the fastening bolt 13 loosened is interposed between the inner peripheral surface of the hollow rotary shaft 1 and the outer peripheral surface of the shaft 2 to be measured, and is projected from the support member 7. Mating pin
19 is press-fitted between the locking bracket 20 and the pressing locking pin 21.

Next, after fastening the shaft 2 to be measured and the hollow rotary shaft 1 by tightening the fastening bolts 13, the eccentricity of the hollow rotary shaft 1 is measured by rotating the shaft 2 to be measured by applying a dial gauge to the measurement surfaces 10 a and 10 b. I do. When the amount of eccentricity and the direction of the eccentricity are determined, the tightening bolt 13 is slightly loosened, the axis of the hollow rotary shaft 1 is adjusted, and the adjusting operation of tightening and fixing the tightening bolt 13 again is repeated, whereby the hollow shaft and the measured shaft 2 are rotated. The axis of the shaft 1 is matched. Thus, the mounting operation is completed.

The axial center of the hollow rotary shaft 1 is adjusted by forcibly displacing the hollow rotary shaft 1 by lightly tapping or the like, and accordingly, the wedge-shaped sleeves 12a and 12b of the fixing means 11 and the angled sleeves 14 and 15 are fixed. This is performed by changing the relative position of.

Next, an operation as a rotary encoder will be described.
When the shaft 2 to be measured rotates, the code plate 4 rotates together with the hollow rotating shaft 1, and the rotation state is detected by the detector 8,
By processing the detection signal, the rotation position and rotation speed of the measured shaft 2 are detected.

At this time, since the shaft to be measured 2 and the hollow rotary shaft 1 are fixed to each other with the center thereof being fixed by the fixing means 11, the eccentricity of the code plate 4 causes the code plate 4 to rotate eccentrically with the rotation of the shaft to be measured 2. (Whirling) does not cause an accumulated pitch error in the detection result.

Further, since the detector 8 is of a laser type and detects narrow beam-like light and dark fringes due to Fraunhofer diffraction of laser light, even if a relatively large gap is provided on both surfaces of the code plate 4, the detector 8 is surely provided. Error-free position detection is possible. Therefore, since the diameter of the hollow rotary shaft 1 and the ball bearing 6 is increased due to the interposition of the fixing means 11, the bearing accuracy is reduced, and there is no possibility that a detection error will occur even if the code plate 4 has a rotational surface runout.

Further, since the support member 7 is fixed only in the rotation direction by the coupling means 17 and can float in the other direction, even if there is a small eccentricity that does not affect the rotation detection, the rotation during rotation is performed. Since the support member 7 can be displaced in accordance with the eccentricity, the bearing 6
There is no possibility that a large load acts on the motor to cause uneven rotation.

In the above embodiment, the connecting means of the support member 7 and the fixing portion 18
Although the example using the engaging pin 19 is shown as 17, as shown in FIGS. 3 (a) and 3 (b), the center of the piano wire 24 is May be fixed, and both ends of the piano wire 24 may be fixed with fixing brackets 25. Also in this case, the same effect can be obtained by the piano wire 24 acting as a rigid body in the rotational direction along the axial direction and acting as a weak elastic body in other directions.

According to the rotary encoder of the present invention, as is apparent from the above description, since the code plate, the detector, the hollow rotary shaft, the bearing, and the support member are combined into a unit to be measured, It can be easily mounted simply by attaching it to the shaft, and the fixing means for fixing the hollow rotary shaft to the shaft to be measured so that the shaft center can be adjusted is provided. By adjusting, the eccentricity can be reduced and the cumulative pitch error can be reduced,
It can also handle high-resolution ones.

In addition, if the detector is a laser type and a narrow beam-like light and dark fringe is detected by Fraunhofer diffraction, even if the gap between the code plate and the detector is set large, there is no possibility that a detection error occurs, By providing the fixing means, the diameters of the hollow rotary shaft and the bearing are increased, the bearing accuracy is reduced, and no detection error occurs even if the surface deflection of the code plate increases.

Further, when the measurement surfaces are provided at both ends of the hollow rotary shaft, the detection accuracy of the shaft center is increased.

Further, by fixing the support member only in the rotation direction and allowing the support member to float in the other direction, a great effect is obtained such that a load does not fluctuate in the bearing due to the rotation and the rotation system is not adversely affected. Demonstrate.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional front view, FIG. 2 shows a coupling means, FIG. 1 (a) is a partial sectional side view, and FIG. FIG. 3 shows another example of the connecting means, FIG. 3 (a) is a side view, FIG. 3 (b) is a bottom view, and FIG. 4 and FIG. It is. 1 ... hollow rotary shaft, 2 ... measured shaft, 4 ... code plate,
6 ball bearing, 7 support member, 8 detector, 10a, 1
0b measurement surface, 11 fixing means, 12a, 12b wedge-shaped sleeve, 13 fastening bolts, 14, 15 chevron sleeve, 17 coupling means, 18 fixing part, 19 Engagement pin,
20: Locking bracket, 21: Lock pin, 24: Piano wire, 25: Fixed bracket.

Claims (7)

(57) [Claims] A code plate, a hollow rotary shaft to which the code plate is fixed, and a support member rotatably supporting the hollow rotary shaft via a bearing and having a detector mounted thereon for detecting the rotational position of the code plate. Fixing means interposed between the inner peripheral surface of the hollow rotary shaft and the measured shaft to fix the hollow rotary shaft to the measured shaft so that the center of the hollow rotary shaft can be adjusted; and a measurement formed on the outer peripheral surface of the hollow rotary shaft. And a rotary encoder comprising: 2. A detector irradiates a laser beam from a laser light source to a code plate, and irradiates a photodetector with light and dark fringes of a Fraunhofer diffraction image generated by a slit regularly formed on the code plate through the slit. 2. The rotary encoder according to claim 1, wherein the rotary encoder is configured to perform the following operations. 3. The rotary encoder according to claim 1, wherein the measurement surface is formed at both ends of the hollow rotary shaft. 4. The rotary encoder according to claim 1, wherein the fixing means comprises a clamping means having a pair of wedge-shaped sleeves and angled sleeves which are attracted to each other by a screw mechanism. 5. A connecting means for fixing the supporting member only in the direction of rotation about the axis of the hollow rotary shaft and connecting the supporting member to the fixed side so as to float in the other direction.
The rotary encoder as described. 6. The coupling means according to claim 5, wherein said coupling means includes an engagement pin projecting from said support member in a radial direction, and a fixed side engagement member circumferentially engaged with said engagement pin. Rotary encoder. 7. A flexible wire rod which is disposed tangentially to a circumference centered on the axis of the hollow rotary shaft and whose intermediate portion is fixed to a support member, and wherein both ends of the flexible wire rod are fixed to the support member. The rotary encoder according to claim 5, further comprising a fixing bracket fixed to the rotary encoder.